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Add more explanation about recursive subpatterns, and make it possible to 
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1 <html>
2 <head>
3 <title>pcretest specification</title>
4 </head>
5 <body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
6 <h1>pcretest man page</h1>
7 <p>
8 Return to the <a href="index.html">PCRE index page</a>.
9 </p>
10 <p>
11 This page is part of the PCRE HTML documentation. It was generated automatically
12 from the original man page. If there is any nonsense in it, please consult the
13 man page, in case the conversion went wrong.
14 <br>
15 <ul>
16 <li><a name="TOC1" href="#SEC1">SYNOPSIS</a>
17 <li><a name="TOC2" href="#SEC2">OPTIONS</a>
18 <li><a name="TOC3" href="#SEC3">DESCRIPTION</a>
19 <li><a name="TOC4" href="#SEC4">PATTERN MODIFIERS</a>
20 <li><a name="TOC5" href="#SEC5">DATA LINES</a>
21 <li><a name="TOC6" href="#SEC6">THE ALTERNATIVE MATCHING FUNCTION</a>
22 <li><a name="TOC7" href="#SEC7">DEFAULT OUTPUT FROM PCRETEST</a>
23 <li><a name="TOC8" href="#SEC8">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a>
24 <li><a name="TOC9" href="#SEC9">RESTARTING AFTER A PARTIAL MATCH</a>
25 <li><a name="TOC10" href="#SEC10">CALLOUTS</a>
26 <li><a name="TOC11" href="#SEC11">NON-PRINTING CHARACTERS</a>
27 <li><a name="TOC12" href="#SEC12">SAVING AND RELOADING COMPILED PATTERNS</a>
28 <li><a name="TOC13" href="#SEC13">SEE ALSO</a>
29 <li><a name="TOC14" href="#SEC14">AUTHOR</a>
30 <li><a name="TOC15" href="#SEC15">REVISION</a>
31 </ul>
32 <br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br>
33 <P>
34 <b>pcretest [options] [source] [destination]</b>
35 <br>
36 <br>
37 <b>pcretest</b> was written as a test program for the PCRE regular expression
38 library itself, but it can also be used for experimenting with regular
39 expressions. This document describes the features of the test program; for
40 details of the regular expressions themselves, see the
41 <a href="pcrepattern.html"><b>pcrepattern</b></a>
42 documentation. For details of the PCRE library function calls and their
43 options, see the
44 <a href="pcreapi.html"><b>pcreapi</b></a>
45 documentation.
46 </P>
47 <br><a name="SEC2" href="#TOC1">OPTIONS</a><br>
48 <P>
49 <b>-b</b>
50 Behave as if each regex has the <b>/B</b> (show bytecode) modifier; the internal
51 form is output after compilation.
52 </P>
53 <P>
54 <b>-C</b>
55 Output the version number of the PCRE library, and all available information
56 about the optional features that are included, and then exit.
57 </P>
58 <P>
59 <b>-d</b>
60 Behave as if each regex has the <b>/D</b> (debug) modifier; the internal
61 form and information about the compiled pattern is output after compilation;
62 <b>-d</b> is equivalent to <b>-b -i</b>.
63 </P>
64 <P>
65 <b>-dfa</b>
66 Behave as if each data line contains the \D escape sequence; this causes the
67 alternative matching function, <b>pcre_dfa_exec()</b>, to be used instead of the
68 standard <b>pcre_exec()</b> function (more detail is given below).
69 </P>
70 <P>
71 <b>-help</b>
72 Output a brief summary these options and then exit.
73 </P>
74 <P>
75 <b>-i</b>
76 Behave as if each regex has the <b>/I</b> modifier; information about the
77 compiled pattern is given after compilation.
78 </P>
79 <P>
80 <b>-M</b>
81 Behave as if each data line contains the \M escape sequence; this causes
82 PCRE to discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings by
83 calling <b>pcre_exec()</b> repeatedly with different limits.
84 </P>
85 <P>
86 <b>-m</b>
87 Output the size of each compiled pattern after it has been compiled. This is
88 equivalent to adding <b>/M</b> to each regular expression. For compatibility
89 with earlier versions of pcretest, <b>-s</b> is a synonym for <b>-m</b>.
90 </P>
91 <P>
92 <b>-o</b> <i>osize</i>
93 Set the number of elements in the output vector that is used when calling
94 <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> to be <i>osize</i>. The default value
95 is 45, which is enough for 14 capturing subexpressions for <b>pcre_exec()</b> or
96 22 different matches for <b>pcre_dfa_exec()</b>. The vector size can be
97 changed for individual matching calls by including \O in the data line (see
98 below).
99 </P>
100 <P>
101 <b>-p</b>
102 Behave as if each regex has the <b>/P</b> modifier; the POSIX wrapper API is
103 used to call PCRE. None of the other options has any effect when <b>-p</b> is
104 set.
105 </P>
106 <P>
107 <b>-q</b>
108 Do not output the version number of <b>pcretest</b> at the start of execution.
109 </P>
110 <P>
111 <b>-S</b> <i>size</i>
112 On Unix-like systems, set the size of the runtime stack to <i>size</i>
113 megabytes.
114 </P>
115 <P>
116 <b>-t</b>
117 Run each compile, study, and match many times with a timer, and output
118 resulting time per compile or match (in milliseconds). Do not set <b>-m</b> with
119 <b>-t</b>, because you will then get the size output a zillion times, and the
120 timing will be distorted. You can control the number of iterations that are
121 used for timing by following <b>-t</b> with a number (as a separate item on the
122 command line). For example, "-t 1000" would iterate 1000 times. The default is
123 to iterate 500000 times.
124 </P>
125 <P>
126 <b>-tm</b>
127 This is like <b>-t</b> except that it times only the matching phase, not the
128 compile or study phases.
129 </P>
130 <br><a name="SEC3" href="#TOC1">DESCRIPTION</a><br>
131 <P>
132 If <b>pcretest</b> is given two filename arguments, it reads from the first and
133 writes to the second. If it is given only one filename argument, it reads from
134 that file and writes to stdout. Otherwise, it reads from stdin and writes to
135 stdout, and prompts for each line of input, using "re&#62;" to prompt for regular
136 expressions, and "data&#62;" to prompt for data lines.
137 </P>
138 <P>
139 When <b>pcretest</b> is built, a configuration option can specify that it should
140 be linked with the <b>libreadline</b> library. When this is done, if the input
141 is from a terminal, it is read using the <b>readline()</b> function. This
142 provides line-editing and history facilities. The output from the <b>-help</b>
143 option states whether or not <b>readline()</b> will be used.
144 </P>
145 <P>
146 The program handles any number of sets of input on a single input file. Each
147 set starts with a regular expression, and continues with any number of data
148 lines to be matched against the pattern.
149 </P>
150 <P>
151 Each data line is matched separately and independently. If you want to do
152 multi-line matches, you have to use the \n escape sequence (or \r or \r\n,
153 etc., depending on the newline setting) in a single line of input to encode the
154 newline sequences. There is no limit on the length of data lines; the input
155 buffer is automatically extended if it is too small.
156 </P>
157 <P>
158 An empty line signals the end of the data lines, at which point a new regular
159 expression is read. The regular expressions are given enclosed in any
160 non-alphanumeric delimiters other than backslash, for example:
161 <pre>
162 /(a|bc)x+yz/
163 </pre>
164 White space before the initial delimiter is ignored. A regular expression may
165 be continued over several input lines, in which case the newline characters are
166 included within it. It is possible to include the delimiter within the pattern
167 by escaping it, for example
168 <pre>
169 /abc\/def/
170 </pre>
171 If you do so, the escape and the delimiter form part of the pattern, but since
172 delimiters are always non-alphanumeric, this does not affect its interpretation.
173 If the terminating delimiter is immediately followed by a backslash, for
174 example,
175 <pre>
176 /abc/\
177 </pre>
178 then a backslash is added to the end of the pattern. This is done to provide a
179 way of testing the error condition that arises if a pattern finishes with a
180 backslash, because
181 <pre>
182 /abc\/
183 </pre>
184 is interpreted as the first line of a pattern that starts with "abc/", causing
185 pcretest to read the next line as a continuation of the regular expression.
186 </P>
187 <br><a name="SEC4" href="#TOC1">PATTERN MODIFIERS</a><br>
188 <P>
189 A pattern may be followed by any number of modifiers, which are mostly single
190 characters. Following Perl usage, these are referred to below as, for example,
191 "the <b>/i</b> modifier", even though the delimiter of the pattern need not
192 always be a slash, and no slash is used when writing modifiers. Whitespace may
193 appear between the final pattern delimiter and the first modifier, and between
194 the modifiers themselves.
195 </P>
196 <P>
197 The <b>/i</b>, <b>/m</b>, <b>/s</b>, and <b>/x</b> modifiers set the PCRE_CASELESS,
198 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
199 <b>pcre_compile()</b> is called. These four modifier letters have the same
200 effect as they do in Perl. For example:
201 <pre>
202 /caseless/i
203 </pre>
204 The following table shows additional modifiers for setting PCRE options that do
205 not correspond to anything in Perl:
206 <pre>
207 <b>/A</b> PCRE_ANCHORED
208 <b>/C</b> PCRE_AUTO_CALLOUT
209 <b>/E</b> PCRE_DOLLAR_ENDONLY
210 <b>/f</b> PCRE_FIRSTLINE
211 <b>/J</b> PCRE_DUPNAMES
212 <b>/N</b> PCRE_NO_AUTO_CAPTURE
213 <b>/U</b> PCRE_UNGREEDY
214 <b>/X</b> PCRE_EXTRA
215 <b>/&#60;JS&#62;</b> PCRE_JAVASCRIPT_COMPAT
216 <b>/&#60;cr&#62;</b> PCRE_NEWLINE_CR
217 <b>/&#60;lf&#62;</b> PCRE_NEWLINE_LF
218 <b>/&#60;crlf&#62;</b> PCRE_NEWLINE_CRLF
219 <b>/&#60;anycrlf&#62;</b> PCRE_NEWLINE_ANYCRLF
220 <b>/&#60;any&#62;</b> PCRE_NEWLINE_ANY
221 <b>/&#60;bsr_anycrlf&#62;</b> PCRE_BSR_ANYCRLF
222 <b>/&#60;bsr_unicode&#62;</b> PCRE_BSR_UNICODE
223 </pre>
224 Those specifying line ending sequences are literal strings as shown, but the
225 letters can be in either case. This example sets multiline matching with CRLF
226 as the line ending sequence:
227 <pre>
228 /^abc/m&#60;crlf&#62;
229 </pre>
230 Details of the meanings of these PCRE options are given in the
231 <a href="pcreapi.html"><b>pcreapi</b></a>
232 documentation.
233 </P>
234 <br><b>
235 Finding all matches in a string
236 </b><br>
237 <P>
238 Searching for all possible matches within each subject string can be requested
239 by the <b>/g</b> or <b>/G</b> modifier. After finding a match, PCRE is called
240 again to search the remainder of the subject string. The difference between
241 <b>/g</b> and <b>/G</b> is that the former uses the <i>startoffset</i> argument to
242 <b>pcre_exec()</b> to start searching at a new point within the entire string
243 (which is in effect what Perl does), whereas the latter passes over a shortened
244 substring. This makes a difference to the matching process if the pattern
245 begins with a lookbehind assertion (including \b or \B).
246 </P>
247 <P>
248 If any call to <b>pcre_exec()</b> in a <b>/g</b> or <b>/G</b> sequence matches an
249 empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
250 PCRE_ANCHORED flags set in order to search for another, non-empty, match at the
251 same point. If this second match fails, the start offset is advanced by one
252 character, and the normal match is retried. This imitates the way Perl handles
253 such cases when using the <b>/g</b> modifier or the <b>split()</b> function.
254 </P>
255 <br><b>
256 Other modifiers
257 </b><br>
258 <P>
259 There are yet more modifiers for controlling the way <b>pcretest</b>
260 operates.
261 </P>
262 <P>
263 The <b>/+</b> modifier requests that as well as outputting the substring that
264 matched the entire pattern, pcretest should in addition output the remainder of
265 the subject string. This is useful for tests where the subject contains
266 multiple copies of the same substring.
267 </P>
268 <P>
269 The <b>/B</b> modifier is a debugging feature. It requests that <b>pcretest</b>
270 output a representation of the compiled byte code after compilation. Normally
271 this information contains length and offset values; however, if <b>/Z</b> is
272 also present, this data is replaced by spaces. This is a special feature for
273 use in the automatic test scripts; it ensures that the same output is generated
274 for different internal link sizes.
275 </P>
276 <P>
277 The <b>/L</b> modifier must be followed directly by the name of a locale, for
278 example,
279 <pre>
280 /pattern/Lfr_FR
281 </pre>
282 For this reason, it must be the last modifier. The given locale is set,
283 <b>pcre_maketables()</b> is called to build a set of character tables for the
284 locale, and this is then passed to <b>pcre_compile()</b> when compiling the
285 regular expression. Without an <b>/L</b> modifier, NULL is passed as the tables
286 pointer; that is, <b>/L</b> applies only to the expression on which it appears.
287 </P>
288 <P>
289 The <b>/I</b> modifier requests that <b>pcretest</b> output information about the
290 compiled pattern (whether it is anchored, has a fixed first character, and
291 so on). It does this by calling <b>pcre_fullinfo()</b> after compiling a
292 pattern. If the pattern is studied, the results of that are also output.
293 </P>
294 <P>
295 The <b>/D</b> modifier is a PCRE debugging feature, and is equivalent to
296 <b>/BI</b>, that is, both the <b>/B</b> and the <b>/I</b> modifiers.
297 </P>
298 <P>
299 The <b>/F</b> modifier causes <b>pcretest</b> to flip the byte order of the
300 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
301 facility is for testing the feature in PCRE that allows it to execute patterns
302 that were compiled on a host with a different endianness. This feature is not
303 available when the POSIX interface to PCRE is being used, that is, when the
304 <b>/P</b> pattern modifier is specified. See also the section about saving and
305 reloading compiled patterns below.
306 </P>
307 <P>
308 The <b>/S</b> modifier causes <b>pcre_study()</b> to be called after the
309 expression has been compiled, and the results used when the expression is
310 matched.
311 </P>
312 <P>
313 The <b>/M</b> modifier causes the size of memory block used to hold the compiled
314 pattern to be output.
315 </P>
316 <P>
317 The <b>/P</b> modifier causes <b>pcretest</b> to call PCRE via the POSIX wrapper
318 API rather than its native API. When this is done, all other modifiers except
319 <b>/i</b>, <b>/m</b>, and <b>/+</b> are ignored. REG_ICASE is set if <b>/i</b> is
320 present, and REG_NEWLINE is set if <b>/m</b> is present. The wrapper functions
321 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
322 </P>
323 <P>
324 The <b>/8</b> modifier causes <b>pcretest</b> to call PCRE with the PCRE_UTF8
325 option set. This turns on support for UTF-8 character handling in PCRE,
326 provided that it was compiled with this support enabled. This modifier also
327 causes any non-printing characters in output strings to be printed using the
328 \x{hh...} notation if they are valid UTF-8 sequences.
329 </P>
330 <P>
331 If the <b>/?</b> modifier is used with <b>/8</b>, it causes <b>pcretest</b> to
332 call <b>pcre_compile()</b> with the PCRE_NO_UTF8_CHECK option, to suppress the
333 checking of the string for UTF-8 validity.
334 </P>
335 <br><a name="SEC5" href="#TOC1">DATA LINES</a><br>
336 <P>
337 Before each data line is passed to <b>pcre_exec()</b>, leading and trailing
338 whitespace is removed, and it is then scanned for \ escapes. Some of these are
339 pretty esoteric features, intended for checking out some of the more
340 complicated features of PCRE. If you are just testing "ordinary" regular
341 expressions, you probably don't need any of these. The following escapes are
342 recognized:
343 <pre>
344 \a alarm (BEL, \x07)
345 \b backspace (\x08)
346 \e escape (\x27)
347 \f formfeed (\x0c)
348 \n newline (\x0a)
349 \qdd set the PCRE_MATCH_LIMIT limit to dd (any number of digits)
350 \r carriage return (\x0d)
351 \t tab (\x09)
352 \v vertical tab (\x0b)
353 \nnn octal character (up to 3 octal digits)
354 \xhh hexadecimal character (up to 2 hex digits)
355 \x{hh...} hexadecimal character, any number of digits in UTF-8 mode
356 \A pass the PCRE_ANCHORED option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
357 \B pass the PCRE_NOTBOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
358 \Cdd call pcre_copy_substring() for substring dd after a successful match (number less than 32)
359 \Cname call pcre_copy_named_substring() for substring "name" after a successful match (name termin-
360 ated by next non alphanumeric character)
361 \C+ show the current captured substrings at callout time
362 \C- do not supply a callout function
363 \C!n return 1 instead of 0 when callout number n is reached
364 \C!n!m return 1 instead of 0 when callout number n is reached for the nth time
365 \C*n pass the number n (may be negative) as callout data; this is used as the callout return value
366 \D use the <b>pcre_dfa_exec()</b> match function
367 \F only shortest match for <b>pcre_dfa_exec()</b>
368 \Gdd call pcre_get_substring() for substring dd after a successful match (number less than 32)
369 \Gname call pcre_get_named_substring() for substring "name" after a successful match (name termin-
370 ated by next non-alphanumeric character)
371 \L call pcre_get_substringlist() after a successful match
372 \M discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings
373 \N pass the PCRE_NOTEMPTY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>; if used twice, pass the
374 PCRE_NOTEMPTY_ATSTART option
375 \Odd set the size of the output vector passed to <b>pcre_exec()</b> to dd (any number of digits)
376 \P pass the PCRE_PARTIAL_SOFT option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>; if used twice, pass the
377 PCRE_PARTIAL_HARD option
378 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd (any number of digits)
379 \R pass the PCRE_DFA_RESTART option to <b>pcre_dfa_exec()</b>
380 \S output details of memory get/free calls during matching
381 \Z pass the PCRE_NOTEOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
382 \? pass the PCRE_NO_UTF8_CHECK option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
383 \&#62;dd start the match at offset dd (any number of digits);
384 this sets the <i>startoffset</i> argument for <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
385 \&#60;cr&#62; pass the PCRE_NEWLINE_CR option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
386 \&#60;lf&#62; pass the PCRE_NEWLINE_LF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
387 \&#60;crlf&#62; pass the PCRE_NEWLINE_CRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
388 \&#60;anycrlf&#62; pass the PCRE_NEWLINE_ANYCRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
389 \&#60;any&#62; pass the PCRE_NEWLINE_ANY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
390 </pre>
391 The escapes that specify line ending sequences are literal strings, exactly as
392 shown. No more than one newline setting should be present in any data line.
393 </P>
394 <P>
395 A backslash followed by anything else just escapes the anything else. If
396 the very last character is a backslash, it is ignored. This gives a way of
397 passing an empty line as data, since a real empty line terminates the data
398 input.
399 </P>
400 <P>
401 If \M is present, <b>pcretest</b> calls <b>pcre_exec()</b> several times, with
402 different values in the <i>match_limit</i> and <i>match_limit_recursion</i>
403 fields of the <b>pcre_extra</b> data structure, until it finds the minimum
404 numbers for each parameter that allow <b>pcre_exec()</b> to complete. The
405 <i>match_limit</i> number is a measure of the amount of backtracking that takes
406 place, and checking it out can be instructive. For most simple matches, the
407 number is quite small, but for patterns with very large numbers of matching
408 possibilities, it can become large very quickly with increasing length of
409 subject string. The <i>match_limit_recursion</i> number is a measure of how much
410 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
411 to complete the match attempt.
412 </P>
413 <P>
414 When \O is used, the value specified may be higher or lower than the size set
415 by the <b>-O</b> command line option (or defaulted to 45); \O applies only to
416 the call of <b>pcre_exec()</b> for the line in which it appears.
417 </P>
418 <P>
419 If the <b>/P</b> modifier was present on the pattern, causing the POSIX wrapper
420 API to be used, the only option-setting sequences that have any effect are \B
421 and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
422 <b>regexec()</b>.
423 </P>
424 <P>
425 The use of \x{hh...} to represent UTF-8 characters is not dependent on the use
426 of the <b>/8</b> modifier on the pattern. It is recognized always. There may be
427 any number of hexadecimal digits inside the braces. The result is from one to
428 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
429 allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
430 valid Unicode code points, or indeed valid UTF-8 characters according to the
431 later rules in RFC 3629.
432 </P>
433 <br><a name="SEC6" href="#TOC1">THE ALTERNATIVE MATCHING FUNCTION</a><br>
434 <P>
435 By default, <b>pcretest</b> uses the standard PCRE matching function,
436 <b>pcre_exec()</b> to match each data line. From release 6.0, PCRE supports an
437 alternative matching function, <b>pcre_dfa_test()</b>, which operates in a
438 different way, and has some restrictions. The differences between the two
439 functions are described in the
440 <a href="pcrematching.html"><b>pcrematching</b></a>
441 documentation.
442 </P>
443 <P>
444 If a data line contains the \D escape sequence, or if the command line
445 contains the <b>-dfa</b> option, the alternative matching function is called.
446 This function finds all possible matches at a given point. If, however, the \F
447 escape sequence is present in the data line, it stops after the first match is
448 found. This is always the shortest possible match.
449 </P>
450 <br><a name="SEC7" href="#TOC1">DEFAULT OUTPUT FROM PCRETEST</a><br>
451 <P>
452 This section describes the output when the normal matching function,
453 <b>pcre_exec()</b>, is being used.
454 </P>
455 <P>
456 When a match succeeds, pcretest outputs the list of captured substrings that
457 <b>pcre_exec()</b> returns, starting with number 0 for the string that matched
458 the whole pattern. Otherwise, it outputs "No match" when the return is
459 PCRE_ERROR_NOMATCH, and "Partial match:" followed by the partially matching
460 substring when <b>pcre_exec()</b> returns PCRE_ERROR_PARTIAL. For any other
461 returns, it outputs the PCRE negative error number. Here is an example of an
462 interactive <b>pcretest</b> run.
463 <pre>
464 $ pcretest
465 PCRE version 7.0 30-Nov-2006
466
467 re&#62; /^abc(\d+)/
468 data&#62; abc123
469 0: abc123
470 1: 123
471 data&#62; xyz
472 No match
473 </pre>
474 Note that unset capturing substrings that are not followed by one that is set
475 are not returned by <b>pcre_exec()</b>, and are not shown by <b>pcretest</b>. In
476 the following example, there are two capturing substrings, but when the first
477 data line is matched, the second, unset substring is not shown. An "internal"
478 unset substring is shown as "&#60;unset&#62;", as for the second data line.
479 <pre>
480 re&#62; /(a)|(b)/
481 data&#62; a
482 0: a
483 1: a
484 data&#62; b
485 0: b
486 1: &#60;unset&#62;
487 2: b
488 </pre>
489 If the strings contain any non-printing characters, they are output as \0x
490 escapes, or as \x{...} escapes if the <b>/8</b> modifier was present on the
491 pattern. See below for the definition of non-printing characters. If the
492 pattern has the <b>/+</b> modifier, the output for substring 0 is followed by
493 the the rest of the subject string, identified by "0+" like this:
494 <pre>
495 re&#62; /cat/+
496 data&#62; cataract
497 0: cat
498 0+ aract
499 </pre>
500 If the pattern has the <b>/g</b> or <b>/G</b> modifier, the results of successive
501 matching attempts are output in sequence, like this:
502 <pre>
503 re&#62; /\Bi(\w\w)/g
504 data&#62; Mississippi
505 0: iss
506 1: ss
507 0: iss
508 1: ss
509 0: ipp
510 1: pp
511 </pre>
512 "No match" is output only if the first match attempt fails.
513 </P>
514 <P>
515 If any of the sequences <b>\C</b>, <b>\G</b>, or <b>\L</b> are present in a
516 data line that is successfully matched, the substrings extracted by the
517 convenience functions are output with C, G, or L after the string number
518 instead of a colon. This is in addition to the normal full list. The string
519 length (that is, the return from the extraction function) is given in
520 parentheses after each string for <b>\C</b> and <b>\G</b>.
521 </P>
522 <P>
523 Note that whereas patterns can be continued over several lines (a plain "&#62;"
524 prompt is used for continuations), data lines may not. However newlines can be
525 included in data by means of the \n escape (or \r, \r\n, etc., depending on
526 the newline sequence setting).
527 </P>
528 <br><a name="SEC8" href="#TOC1">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a><br>
529 <P>
530 When the alternative matching function, <b>pcre_dfa_exec()</b>, is used (by
531 means of the \D escape sequence or the <b>-dfa</b> command line option), the
532 output consists of a list of all the matches that start at the first point in
533 the subject where there is at least one match. For example:
534 <pre>
535 re&#62; /(tang|tangerine|tan)/
536 data&#62; yellow tangerine\D
537 0: tangerine
538 1: tang
539 2: tan
540 </pre>
541 (Using the normal matching function on this data finds only "tang".) The
542 longest matching string is always given first (and numbered zero). After a
543 PCRE_ERROR_PARTIAL return, the output is "Partial match:", followed by the
544 partially matching substring.
545 </P>
546 <P>
547 If <b>/g</b> is present on the pattern, the search for further matches resumes
548 at the end of the longest match. For example:
549 <pre>
550 re&#62; /(tang|tangerine|tan)/g
551 data&#62; yellow tangerine and tangy sultana\D
552 0: tangerine
553 1: tang
554 2: tan
555 0: tang
556 1: tan
557 0: tan
558 </pre>
559 Since the matching function does not support substring capture, the escape
560 sequences that are concerned with captured substrings are not relevant.
561 </P>
562 <br><a name="SEC9" href="#TOC1">RESTARTING AFTER A PARTIAL MATCH</a><br>
563 <P>
564 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
565 indicating that the subject partially matched the pattern, you can restart the
566 match with additional subject data by means of the \R escape sequence. For
567 example:
568 <pre>
569 re&#62; /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
570 data&#62; 23ja\P\D
571 Partial match: 23ja
572 data&#62; n05\R\D
573 0: n05
574 </pre>
575 For further information about partial matching, see the
576 <a href="pcrepartial.html"><b>pcrepartial</b></a>
577 documentation.
578 </P>
579 <br><a name="SEC10" href="#TOC1">CALLOUTS</a><br>
580 <P>
581 If the pattern contains any callout requests, <b>pcretest</b>'s callout function
582 is called during matching. This works with both matching functions. By default,
583 the called function displays the callout number, the start and current
584 positions in the text at the callout time, and the next pattern item to be
585 tested. For example, the output
586 <pre>
587 ---&#62;pqrabcdef
588 0 ^ ^ \d
589 </pre>
590 indicates that callout number 0 occurred for a match attempt starting at the
591 fourth character of the subject string, when the pointer was at the seventh
592 character of the data, and when the next pattern item was \d. Just one
593 circumflex is output if the start and current positions are the same.
594 </P>
595 <P>
596 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
597 result of the <b>/C</b> pattern modifier. In this case, instead of showing the
598 callout number, the offset in the pattern, preceded by a plus, is output. For
599 example:
600 <pre>
601 re&#62; /\d?[A-E]\*/C
602 data&#62; E*
603 ---&#62;E*
604 +0 ^ \d?
605 +3 ^ [A-E]
606 +8 ^^ \*
607 +10 ^ ^
608 0: E*
609 </pre>
610 The callout function in <b>pcretest</b> returns zero (carry on matching) by
611 default, but you can use a \C item in a data line (as described above) to
612 change this.
613 </P>
614 <P>
615 Inserting callouts can be helpful when using <b>pcretest</b> to check
616 complicated regular expressions. For further information about callouts, see
617 the
618 <a href="pcrecallout.html"><b>pcrecallout</b></a>
619 documentation.
620 </P>
621 <br><a name="SEC11" href="#TOC1">NON-PRINTING CHARACTERS</a><br>
622 <P>
623 When <b>pcretest</b> is outputting text in the compiled version of a pattern,
624 bytes other than 32-126 are always treated as non-printing characters are are
625 therefore shown as hex escapes.
626 </P>
627 <P>
628 When <b>pcretest</b> is outputting text that is a matched part of a subject
629 string, it behaves in the same way, unless a different locale has been set for
630 the pattern (using the <b>/L</b> modifier). In this case, the <b>isprint()</b>
631 function to distinguish printing and non-printing characters.
632 </P>
633 <br><a name="SEC12" href="#TOC1">SAVING AND RELOADING COMPILED PATTERNS</a><br>
634 <P>
635 The facilities described in this section are not available when the POSIX
636 inteface to PCRE is being used, that is, when the <b>/P</b> pattern modifier is
637 specified.
638 </P>
639 <P>
640 When the POSIX interface is not in use, you can cause <b>pcretest</b> to write a
641 compiled pattern to a file, by following the modifiers with &#62; and a file name.
642 For example:
643 <pre>
644 /pattern/im &#62;/some/file
645 </pre>
646 See the
647 <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
648 documentation for a discussion about saving and re-using compiled patterns.
649 </P>
650 <P>
651 The data that is written is binary. The first eight bytes are the length of the
652 compiled pattern data followed by the length of the optional study data, each
653 written as four bytes in big-endian order (most significant byte first). If
654 there is no study data (either the pattern was not studied, or studying did not
655 return any data), the second length is zero. The lengths are followed by an
656 exact copy of the compiled pattern. If there is additional study data, this
657 follows immediately after the compiled pattern. After writing the file,
658 <b>pcretest</b> expects to read a new pattern.
659 </P>
660 <P>
661 A saved pattern can be reloaded into <b>pcretest</b> by specifing &#60; and a file
662 name instead of a pattern. The name of the file must not contain a &#60; character,
663 as otherwise <b>pcretest</b> will interpret the line as a pattern delimited by &#60;
664 characters.
665 For example:
666 <pre>
667 re&#62; &#60;/some/file
668 Compiled regex loaded from /some/file
669 No study data
670 </pre>
671 When the pattern has been loaded, <b>pcretest</b> proceeds to read data lines in
672 the usual way.
673 </P>
674 <P>
675 You can copy a file written by <b>pcretest</b> to a different host and reload it
676 there, even if the new host has opposite endianness to the one on which the
677 pattern was compiled. For example, you can compile on an i86 machine and run on
678 a SPARC machine.
679 </P>
680 <P>
681 File names for saving and reloading can be absolute or relative, but note that
682 the shell facility of expanding a file name that starts with a tilde (~) is not
683 available.
684 </P>
685 <P>
686 The ability to save and reload files in <b>pcretest</b> is intended for testing
687 and experimentation. It is not intended for production use because only a
688 single pattern can be written to a file. Furthermore, there is no facility for
689 supplying custom character tables for use with a reloaded pattern. If the
690 original pattern was compiled with custom tables, an attempt to match a subject
691 string using a reloaded pattern is likely to cause <b>pcretest</b> to crash.
692 Finally, if you attempt to load a file that is not in the correct format, the
693 result is undefined.
694 </P>
695 <br><a name="SEC13" href="#TOC1">SEE ALSO</a><br>
696 <P>
697 <b>pcre</b>(3), <b>pcreapi</b>(3), <b>pcrecallout</b>(3), <b>pcrematching</b>(3),
698 <b>pcrepartial</b>(d), <b>pcrepattern</b>(3), <b>pcreprecompile</b>(3).
699 </P>
700 <br><a name="SEC14" href="#TOC1">AUTHOR</a><br>
701 <P>
702 Philip Hazel
703 <br>
704 University Computing Service
705 <br>
706 Cambridge CB2 3QH, England.
707 <br>
708 </P>
709 <br><a name="SEC15" href="#TOC1">REVISION</a><br>
710 <P>
711 Last updated: 11 September 2009
712 <br>
713 Copyright &copy; 1997-2009 University of Cambridge.
714 <br>
715 <p>
716 Return to the <a href="index.html">PCRE index page</a>.
717 </p>

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